Free pumping system



Oct. 18, 1955 R. w. SCHOEN ETAL FREE PUMPING SYSTEM Filed April 5, 1954 3 Sheets-Sheet l Oct. 18, 1955 R, w. SCHOEN ET AL FREE PUMPING SYSTEM 3 Sheets-Sheet 2 Filed April 5, 1954 lh/VEA/TOR-i v R0661? w sch/05M,

RHLPH B. TIL/V5): 5v QTrcPn/E/ Patented Get. 18, 1955 FREE PUMPING SYSTEM Roger W. Schoen, Mineral Wells, Tex., and Ralph B.

Tilney, Clayton, M0,, assignors to Alco Valve ;Cornpany, St. Louis, Mo., a corporation of Missouri Application April 5, 1954, Serial No. 420,854 Claims. e1. 10346) The present invention relates to a free pump system. Free pumps are particularly useful in connection with deep well pumping operations. There are pumps available that are adapted to be lowered to the bottom of the well and there be operated by means of hydraulic pressure conditions developed in a column of power oil piped down from the surface. Such hydraulic pumps do not require a long mechanical pump rod reciprocating throughout the length of the well.

The so-called free pump was developed as an improvement in the hydraulic pumping arrangement because, in order to remove the hy raulic pump from the well, the entire power oil tubing had to be drawn out of the well to bring the pump to the surface. The free purnp is not rigidly attached to the bottom of the power oil tubing,

but rather is made to be slidable through tubing to the bottom of the well by gravity assisted, as may be necessary, by application of hydraulic pressure above it. Conversely, it is made slidable back from the bottom of the well to the surface by a reversal of hydraulic pressure conditions in the well so that relatively high pressure acts beneath the pump to drive it upwardly to the surface. Thus, a free pump is not mechanically bound to the bottom of the well, nor mechanically bound to a long string of tubing which must be drawn out of the well before the pump can be removed.

In a free pump arrangement, there must be two separate conduits for oil, one to conduct the power oil down to the pump and the other for conducting the production oil plus exhaust power oil back to the surface. Heretofore, the free pump arrangements have had to have the pump reciprocable in the power oil tube, as distinguished from the production oil tubing. This is to reverse normal hydraulic pump practice, and it requires the high pressures to be applied to the large tubing, and the larger volume of liquid to be transmitted in the relatively smaller tubing. This reversal is inefficient for obvious reasons.

One of the objects of the present invention is to provide a free pump system in which the pump is in the relatively larger production oil tubing rather than in the small power oil tubing, with the increased efiiciencies resulting therefrom. To this end, the present pump system includes a free pump and a four-way valve at the surface connected into the power oil and production oil tubing so that it can reverse the piping of the power oil and production oil. By this ability to reverse the application of pressure to the two columns of oil, pressure can be applied to the production oil column and the power oil can be relieved of the pressure. There is a valve arrangement associated with the pump itself that acts responsively to temporarily shifting of pressure to the production oil column by means of the four-way valve, to cause power oil to be applied beneath the pump so as to lift the pump out of the well.

The broad improvement represented in the previous paragraph is supplemented by numerous improvements in the specific mechanism involved, as will appear from the description to follow.

In the drawings:

Figure l is a view primarily in vertical diametrical section of the upper part of a pump apparatus embodying the present invention;

Figure 2 is a similar vertical section of the next lower, medial part of a pump apparatus embodying the present invention;

Figure 3 is a vertical diametrical section of the next lower bottom part of a pump apparatus embodying the present invention;

Figure 4 is a transverse section on the line 4-4 of Figure l;

Figure 5 is a transverse section on the line 55 of Figure 1;

Figure 6 is a transverse section on the line 66 of Figure 1;

Figure 7 is a transverse section on the line 77 of Figure 1;

Figure 8 is a transverse section on the line 88 of Figure 1;

Figure 9 is a fragmentary vertical section of the part shown at the bottom of Figure 1, with the valve locked down; and

Figure 10 is a diagrammatic view of the pumping system, broken away in sections so as to foreshorten it.

In the drawings, a Well tubing 10 is represented, it being adapted to encase a well. Within the lower part of the tubing 10, near the bottom of the well, there is an offset shoe fitting 11 that is externally threaded at 12 to receive a mud anchor, and that is internally threaded at 13 to receive a gas anchor, which parts form no part of the present invention. The shoe 11 has the foregoing parts arranged concentrically with the tubing 10, and it has an upper, internally threaded sleeve 14 that is olfset from the center of the tubing.

The sleeve 14 of the shoe 11 is threaded onto the lower end of a standing valve barrel 16 into which is fitted a standing valve generally designated at 17. The standing valve includes a headed plug 18 slidable in the barrel 16 to descend and rest upon a shoulder in the upper part of the shoe 11. The reduced end of the plug 18 is externally threaded so as to receive a cage 19 that has appropriate external packing sealing it within the valve barrel 16. The cage 19 contains the check valve 20 in a medial portion that has vertical slots. The valve can seat upon a valve seat 21 when it is down in the lower part of the cage. The valve 20 can lift upwardly as far as a stop 22 that is part of the upper portion 23 of the cage 19, to permit flow of oil upwardly through the plug 18, the valve seat 21, the slotted cage and the upper fitting 23. The top fitting 23 is ported as at 24 and has a spearhead 25 projecting upwardly so that it may receive a pulling tool, as is known in the art.

Above the standing valve 17 there is a sealing tube 26 slidably fitted Within the barrel 16 and provided with suitable external packing as illustrated.

The barrel 16 is externally threaded at its upper end and attached into a coupling 3%. The upper end of the coupling 30 is, in turn, threaded to receive the lower end of a barrel 31. The barrel 31 is an outer barrel in which a production unit 32 is supported. That production unit comprises a hydraulic motor and a pump, such as a sucker rod pump, operated by the motor, with appropriate check valves to control the direction of flow of the oil. See, for examples, applications Serial No. 373,955, filed August 13, 1953, and Serial No. 384,732, filed October 7, 1953.

The inner diameter of the barrel 16 is less than that of the barrel 31. This diiference is important because, as will appear, it provides a hydraulic pressure area differential used in driving the assembly to the surface.

As illustrated, the production unit 32 is threaded onto the upper end of the spacing tube 26 so as to provide a ra age-s a 7 continuous passage from the Valve 17 into the production unit 32. It will be understood that the production unit delivers production oil into the space 33 between the e control valve housing 35 has a lateral Qffset38 that receives the lower end of power oil tubing 39. This "power oil tubing also is "continuous to the surface.

As shown in Figure 2, the upper end of the produc- 'tion unit barrel 32 receives a threaded end of a nipple 41], and that nipple, at its upper end, is threaded 'iritothe lower end or a cage 42 that is slidably fitted within the housing 35. This cage 412 has an outer diameter greater th n that (if the production unit32 andthe' siealing'sleeve 2 6fa'nd this difie'rence is used in the hydraulic drive of the assembly to the surface. The cage 42 has a plurality "of pa ages jcireularly arranged around a center'part 45 in hi ch' the nipple 40 is threaded. Theproduct'io'noil 1n the space or passage '33 outside the production unit hajjel a d within the outer barrel 31'can be conducted through the'pa'ssa'ges43. v

The'eehter portion 45 of the cage '42 also receives the low'r erid of a tube 47 that'is slidably inserted "into "a fcent'er hereof the part 45 to rest upon 'the top of the fnipple 40, as illustrated in Figure 2 Appropriate packing is provided as illustrated. This tube '47 're'giste'rswith the 'int'eriorpassage of the 'nip'pleAQ and correspondingly may slidably fit into a central tubular part 66 of the side valve barrel 54. The central part 66 projects downwardly into the upper end of the packing ring 48, as appears at the top of Figure 2. The interior of the tube 47 thereby communicates into a bore 67 along the axis of the member 55. This bore 67. registers with a lateral passage 68 shown at the bottom of Figure 1 and in Figure 7. This passage 68, in turn, connects through the reduced partof the control valve barrel 54 and, as ;il'- lustrated, registers with' he passage '65 leading to the power oil tubing 39. This lateral passage 68 is controlled by a valve, as willappear.

The lower part of the barrel 54 has a "series-of verti-f cal bores 70 circularly arranged around the center bore 67 '(Figures 1, 7 and 8). Each of these passages 70 connects at its upper end with a radial passage 71 that connects into the bore 67.

' As shown in Figures 1, 5 and 6, there is'a plurality of radial passages 73 spaced above the radial .passages'li. Each passa'ge 7 3 registers with the bottom'endof'a vertical "bore 7 4; The bores 74 are circularly disposed arouud e ut ral bore 67 and extend upwardly to them-p of" I inner barrel 53, at which point theyopen into the interior the interior pa$ag f the productionunit 32. The upper end "of the 'tube47 projects th'rq l h andabo've an enlarged opening in the top of the cage 42 This open ing is lar'ge'enou 'to receive a sleeve48 and to 'leave a between the interior of the sleeve and 'theexter'ior fi t s tube r sleeve 48 is threaded into the upper "e'ndbt the i42p I ring eli' to clamp the packing against theto'p of the cage 321" The 'packin'gsQ 'bears'sealingly within the interior housing35. The'upper part of the sleeve tS'ha's H ang'e sl ab oveiwhich it is e i ternally th'readed foree e we end cra-ap e se ba r 4- W "lower part 53 of the inside b 'rrel "54 has a"s'lidah1'e "fit "within the casing 35. Similarly, the upper part 55 of th barrel 54 has such a tit within the casingfbut the r'inediatejportion has a reduced outside diameter. Tlie pQrtionSS receives the lower 'fiarigediandthre'aded end of a packing retainer 56 that is irroun ed packing eieme'iits s'l and' 58 which provide for a se'alin'g fit within the' casing The casing internal diameter. Theup'per'endj oftliepackin'gesis It has 'a shoulder"49 engageable over aipaekiiig ee-t ance by a packirig ring" S Q threaded 'hnt the packing fretainer SG. upper retainer "59 has aspear'head'tifl "part "of the fitting, this providing'tor communication iner 56 09 the upper from the interior-of the packing'reta I The :lateral projection 38 the valve easing i previds an elongated passage the iipp'efend ofwliich connects into the lower end of the power oil tubing 39.

The passage 65', lso registers and' is'substaritially 'coex- "tensive along the axis'with the reduced pa ofthe'inside barre T153 so that there "is ommu icatioa all the way aroundth'at barrel. 7 V U h V v "R n rig toF u e 2, h 1 47 ha t i -P 1.9

'2 l t a s somewhatenlar'ged and 'providd'with packing so'that it d; to 7 receive a pulling tool,

of the paehing retainers 56-59, and"ultimately into'the interior of the production oiltubi'ng 37.

'Iheaxial bore .67 inth'e control valve housing's t-is aapflted receive the upper landof a valve'generally in dica'ted'at 79. *It has a lower land slidablewithin the "passage 67." Below the land 80"there is a downwardly projecting pin 81 provided'with cireular'grooves, and'a by athreaded cellar 85 By this meansgthere ca b'e s'om'e axial 'adjustm'entof these parts; The upper'end'ot itslower'end against'a shoulderjiu' anupper, enlargedpart l 8' t the bore 67, which enlarged part forms apressure chamber'as'will appear.

The head 86 of the flanged stem 84 is'p'rovidedwith angular pens '89 that "openjinto 'a central recess in the top "of the head. The recess, in "turn, registers with'a 'eor- 'res'pondingcentralbore in a plug 90 that is-threadedin it" 'tl'ie upper end of the'insidebarreFM. Theplug 90 is ided with a central bore-of 'varying diameters 'a sin- K x 'dic'ated. This'bo'reis'closed at'its top by'a tubluarplug '91 thathas a'eheck valve 'seat at its lower end. Th'eball check valve 92 co'acts with thissea'g'being-urged'upwardly byafianged member 93' acted upon by a compression spring 9 1, as is iridicated in Figure l.

7 By the foregoing arrangement,the'controlvalve is 3 ."normally held upwardly with its head "86 aga'nstfthe plug ,0. The'val've 79 maybe forced downward against n'valve 79 ean'be' 'r e l din a lower position. To this shown'p'articularlyin Figuresffi and 9, the hoto reduced intermediate part of the control vaive "springfi. and 'a'reta'ning'device is provided so "triers barrel has a'jradial bore9 6 con'neeting 'a'iiial bor'eti'l "The radial b ore receives 'a 'recipr'ocable're.

"tainerplug'98, This plug 98 is of varying' diamete'rs'so "thatfits inner end"projects'into thebore' 67' through 'a reduced inner "end of the radial 'bo'r'e 9 firand the inner je'nd 'of the plug28 is provided with vertical-notche the'valve.

Within 'the larger parts-of the bore the plug is share ab r w ei d age a l sp th t urges he Plus ar y n' th man rai us- "timed. Thereds a retaining member" ltilthreaded nto the outermost part'of the plug receiving -hore to held these parts in place. 103, and the retaining cap 102 has a larger hold 104 so The P 98 as eu aii las s that certain amounts of liquid may flow through these parts. Also, there is a vertical bore 105 connecting down into the spring chamber of the bore 96 for a purpose to appear. The upper end of the passage 105 opens into one of the transverse passages 73.

There is also a bleed port 106 that extends upwardly through the upper land of the valve 79 for a purpose to appear.

When in position, the well tubing is in place and the main pump tubing is inserted down through the well casing 10. That is to say, the offset shoe 11 is in the bottom of the Well with the mud anchor and gas anchor attached thereto and positioned in the conventional manner. The assembly, including the valve 17, is located in the bottom of the tubing 16, and the entire string consisting of the tubing 16, the coupling 30, the tubing 31, the coupling 34, the valve housing 35, the coupling 36, and the various lengths of tubing 37 are in place and extend to the surface. Similarly, the power oil tubing 39 is in place and extends to the surface.

At the surface there is piping 371 (Figure 10) connecting the production tubing 37 to the four-way valve 110, and likewise there is piping 391 connecting power oil tubing 39 to the four-way valve. Power oil is brought to the four-way valve by piping 392, and production oil is conducted to tanks by piping 372. The piping 392 connects to a source of hydraulic pressure in order that the power oil may be subjected to pressure conditions. This is explained in the copending applications referred to, and is conventional to the hydraulic type of the well pump.

In the present case, the four-way valve is designed so that it normally will connect the piping 392 and the source of hydraulic pressure with the power oil tubing 39, and will connect the piping 372 with the production oil tubing 37; but it may be reversed so as to connect piping 392 and the hydraulic pressure source to the production oil and to connect the power oil tubing 39 to the tanks. Consequently, although ordinarily the oil in the power oil tubing 39 is subjected to pressure continuously or intermittently in accordance with the type of pump and motor employed, this source of pressure may alternately be applied to the production oil in the tubing 37.

Operation Prior to inserting the pump into the well tubing, the tube 26 is connected to the production unit 32, and the production unit 32, in turn, is connected to the nipple 40. That nipple 40 is connected into the bottom of the cage 45. The packing retainer 48 and the packing 50 are connected to the nipple 41' as indicated. The tube 47 is inserted and the control valve housing 54 is connected to the packing retainer 48. Above this the packing members 56 and 59 are connected together so as to retain the packing rings 57 and 58, and the packing assembly is secured to the housing 54.

The foregoing, therefore, provides for the attachment together, prior to their introduction into the previously mentioned pump tubing, of the various components of the pump including the production unit and the reversing valve mechanism. With appropriate tools, such as a grapple engageable with the spearhead 69, the foregoing assembly is then inserted into the tubing 10 and lowered below the surface.

The four-way valve 119 may be operated then to connect the power oil supply into the top of the tubing 37. This will apply pressure to the oil in the tubing 37, down past the legs 61 and into the interior of the packing re tainers 59 and 56. It then will be applied down into the passages 74. However, it also is applied downwardly against the check valve 92, displacing it so as to fill the interior of the pressure chamber 88 with high pressure oil. Therein the net area downwardly is greater than the effective unbalanced net area upwardly so that this hydraulic pressure forces the valve 79 down to the position illustrated in Figure 9, which is such that the upper land 6 83 cuts oi the lateral passages 73 while the lower land moves down below the lateral passage 68.

With the valve 79 in that position, the communication from the production tubing 37 downwardly past the valve is prevented. Consequently, hydraulic pressure applied to the oil in the tubing 37 forces the whole assembly downwardly. Any fluid pressure below the assembly may escape upwardly past the lowered valve 79, into the tubing 39, wherein there is only gravity head pressure.

The descent of the pump and valve assembly to the bottom of the well is completed when the member 26 comes to rest on the top of the valve cage 19. Thereupon, the parts occupy the positions illustrated in Figures 1, 2 and 3 save for the fact that the valve 79 is down.

From the practical standpoint, the pump should be lowered into the pump tubing with oil in the tubing.

When the foregoing is accomplished, the four-way valve 113 is turned to relieve power oil pressure from both tubing 37 and tubing 39. When the four-way valve is operated to relieve the power oil pressure from the top of the valve 79, the spring 87 becomes sufiicient to cause the valve 79 again to rise. The check valve 92 seats, but the spring nevertheless can cause the oil within the pressure chamber 76 to be expelled through the bleed passage 106 down through the upper land 83 of the valve. Consequently, the valve will rise to the position shown in Figure l.

The foregoing requires only a brief interval. The operator waits an appropriate time to permit the valve 79 to rise, and then shifts the valve 116 to connect power oil pressure to the tubing 39, and to connect the production tubing 37 to the tubing 372.

In the position shown in Figure l, the power oil from the pine 39, which is under greater pressure, is connected down through the passage 65 of the lateral extension 38 on the casing 35, thence through the lateral passage 68 to the interior valve bore passage 67 below the valve 79. Power oil continues down through the tube 47 and the nipple 49 to the interior of the upper side of the production unit 32. From the other patent applications referred to, it will be understood that the power oil is introduced into the top of a pump motor in which there is an appropriate reversing valve mechanism that alternately admits this power oil pressure, and then admits production oil pressure to the upper side of a piston system while maintaining power oil pressure constantly on the lower side of the piston, which correspondingly is caused to ascend and descend, thereby operating the pump. (Of course,

ther hydraulic pump systems are known, which operate by valving the high pressure oil and the lower pressure production oil into a hydraulic pump motor.)

By this pumping action, production oil is drawn up from the bottom of the well past the valve 20 into the spacer 26. From this spacer it is drawn into the pump and then is expelled into the production oil space 33 beween the unit 32 and the tubing 31. The pump forces the production oil to the top of the space 33 whence it moves upwardly through the outer series of passages, including the passages 4-3 in the cage 42, and thence up within the packing retainer 48, around the outside of the tube 47. It moves into the lower part 53 of the member 54 and thence by way of the passages 70 to the transverse passages 71. With the valve 79 down, the lower land 80 thereof causes this production oil to be admitted upwardly to the transverse passages 73, the vertical passages 74, the interior of the packing retainer 5659, and on upwardly to the production tubing 37.

As the pump continues to operate, it forces the production oil, plus the used power oil, up through the tubing 37 as indicated.

When it is desired to bring the pump assembly to the surface, the four-way valve 110 is caused to reverse the connections to apply the pressure to the oil in the tubing 37 and to relieve the pressure on the tubing 39. This pressure will cause the check valve 92 within the plug pressure chamber 7 figures 8 and h ep '7 t to open s'othat' high pressure will The introduced into the 8'8' a bove the valve -79. Again, the

valve 79 -ii e'scerid*-until it I reaches the -position illusr ed in Figuref9. At this 'me the loc'king plunger98 s still'in its' r'etracted position u'nder the influence opt-the spring-T01. fiWhenthe'valve 79isdown, the power oil tubing 39connects -down=by "way -of the'passage -65, the "transversepassage 68, into the. transversepassages 71, the vertr aPpaSsag'esVO, -and"=t-hence *douiiwardly 'thrc qughoot the productionoil space 33.

With the 'valvef79 in 'itslower'position, the producttion 11 "tubing "37 is cut" oil "from conununication to belovv the control 'valve housing 54 at the upper land 83 of the valve79"which -disposed across jth'e trans- 'v'e'r'se 'passages :Aft'er four-way valve'hasbecn held in the forefojra;perio1d long enough to insure that i z a os i 23Ppliei1to'the'tubing37 has forced'the high pressure =valve79fful ly down, theIfour-wavvalve is restored to 5 its original position and the pressure is applied to the iintheflpower o'il .mbingss, whereas the production toil vtuhi'ngYW 'is relieved of pressure so that .thepressure therein is merely the hydrostatic head from the surface down'tothe pump. i V '7 Astsoon as-pressure again exists on the power oil tubing 39, this pressure is delivered through the passage :65. The lower: end of the reducedportionof the housmg v54 receives the plug l02, so that fluid from the passage 65,-rnayalways'flow into the'port 104-shown in 9, to the head of the locking plug 98. Owing to thetfact that the hole 104 has considerably less resistance to flow than does the bleeder port 103 98, the plug will .be forced inwardly a a h sp n groovesltlll against the grooves in the depending pin :81 on the bottom of thevalve. Thepower oil pressure will continue tobe applied to the plug 98, holdingit in lockingpositionso that thervalve 79 is maintained in its o e ;rw t m v During the interval between the time that the fourway valve llll'relieves valve 79; and the time that the locking plug 98 can be forced into locking :position, into i its lower position by hydraulic dampener action. -In forcing the valve down, the :filled with oil which passed the check valve 92. As soon-as the power oil vpressure was relieved in the tubing 37, the spring 187 pr tended to v force the valve 79=upwardly. (Such-upward movement reduces the size of the pressure chamber 88-so'that' oil enable-the valve to rise; -However,- the check :valve 92 gseats prider thes'e conditions so as to preventifree escape refoil-from the pressure chamber 76, leaving only the restricted passagetmfiforescape of oil therefrom, The wbleeder passagediioi is so small vthat the flow therethrough ;pe r-rnitsonly. a very-slow ascent'of the'valve 79'and'no -substantial movement of the-valve 'will have occurred infl-thei intervalbetween the 'shiftingof the check valve pressure from the tubing 37 and to apply relievingathe. V

ing pr essurerto thetubing 39. The multiple grooves on Lthe pin illz andthe plug 98, however, will insure'a'locking action for-several. positions ofthe valve 79, and thus permit a: certain tolerance ,in' the foregoing action.

Bvtheforegoing action, the control valve 79 is depressed .an d lockeddown to remain down vas long as pressure continues in the tubing39.

When the poweroilpressureisapplied withtthe valve in J its ",lower position, such pressure is blocked i by vthe lower land80'of the valve 79 from its usual insidepas- V vsage to the production unit,-;and insteadis delivered via Qthepassages "It iandlfifl to the ,i v .7 r-P ss e hat-Par- .mally receive production oil.

e k I v n 7 It is transmitted down outside the .produetion unit 32..

w 7 lt is 'seale d flby the :packing. rings around the seal i g sleeve .26,;-frorn.passing below this sleeve.

101 and 'will be caused to bring its .the pressure on the top 'of'the ,pressure chamber 188 must be"expell ed therefrom to the valve 79 is restrained" The sleeve 26 -is of less *so that there is a net ar-ea idifierentialiproducing upward net hydraulic force. 7 -'ditions as stated-:cause the e ntire assembly :to'f litheisiefllfl 26, the production unit 32 =and'athe valve Z'hOHSiHgPSZl :to,

"beforce'd upwardly, they being rallsattach'ed together.

Presently, 'the :assembly will be .driven iupward :until the retainer 102 is above the top of the passage $65,

Prior -to this,t he lower-edge of the tcage'i42 Will3ascend above-the lower end of the passage '6 5,';so thatxpower oil pressure continues :to force :theassembly upward.

- And it becomes unnecessaryi for the valve 79 rtoi'remain 1 tubing. Therefore, that"tubing may be-small, asLis desir able 7 I J I V What'is-clai med is: V

l. 'A free pump apparatus' including a housing havin'g a through passage :and a lateral passage-rconnecting into" "the throughrpassage betweenthe upper and lower ends, thereof, the'uppe'r end of l connectible with production 011 tubing leading to the.

the through =-pa'ssa ge bein'g surface and "the lower .end being connectihle to like tubing to enclose a production unit-at the bottom of the well/said -'bing and the through passa'ge providing a "uniformpassage to the surfacefpower oil tubing connectingf'rom the lateraljpass age of -the housing to the surface; a production a unit" within 5 the lower production oil tuhing with a sealing sleeve attached to the bottorn thereof, "the sleeve lhaving fa diameter less than that of the production oil tuhing and anextension-below the lower production-oil tubing into which the sealing sleeve slidably -fits and substantially seals; a check-valve in the :eXtension below-the :sealing'sleeve, the -produetion;unit

having a size less thanf'that of the through-passage to provide a fluid passage' 'be-tween ,it-self and the tubing; a valve barrel having aslidable fit within the through passage and extending above and below the lateral passage of the: housing with sealing: means above/and below: 7- that vpassage: sealing between the housing and theibarrel; V

a valve in the v-valverbarrel, an upper :passageconneetin'g :downQfrom'ltheitoprof the barrel to thevalve, thepassage opening upwardly td the production-oil tubing; two lower. passages lbelowthe valve, comprising .a lowers'pro- -duction oil passage openinghdownwardly :to thelspace around" the: production unit, and a lower, separate :power oil I passage connecting into the production uniti- :a side .passage'into the-valve barrel for connection with ithe lateral passage of the housing, the valvevhavingm first positiomconnectingtthe upperpassage with the lower-prw Eduction oil i passage while also connecting the side tpassage with the lower power oil passage-and the valve Thaving a secon'd position connecting the side passage with the lower production oil passage andclosingithe-npper passage and the lower power oilfpassagey fluid pressure -:means to movethevalve from thetfirst position tosecond position responsive to high pressure applieditozithe'ipro- 'Vductionoil passage;

valve into first-position and yieldablenonly to pressures above normal head of the iproduction oil i passage; and means "to retain the valve tinasecond positionragainst action of the yieldablefmeans, so that the power oil introduced into :the r lower production oil .passa'ge inlay act-upwardly on a larger area :than ,downwardlyrand :drive the r pump :v-assembly upwardly :from' the well, :tflie -lateral passage having connection withthe side passage throughout an axial distanceisufficient to permit :the lateral passagevto connect below thelower housinglsealing hefere the side passage 3 moves beyond the upper end of the lateral passage. i in diameter than the housing :5 4,

'li'herefore, ipressure con-v to descend in thefipoiverioil yieldable means;normally. urging the 2. In a free pump: an assembly comprising a production unit and a valve, the assembly being sized to pass downwardly through well tubing to the lower end of a well, the assembly having a side passage for connection with a power fluid tube for introducing power fluid into the production unit to operate the pump and drive production fluid out the well tubing, the assembly having a lower end of reduced diameter having a sealing fit with well tubing below the previously mentioned tubing at the lower end of the well, and the assembly having a sliding, piston-like fit into the well tubing above the sealing fit, the assembly having a larger size above the sealing fit so as to provide a space having an area diiferential such that hydraulic pressure can drive the pump upwardly, a valve in the assembly movable to connect the power oil tubing into the area-difierential space, and means in the assembly to move the valve to {enable power oil to drive the pump assembly from the well.

3. The combination of claim 2, wherein the valve moving means comprises a fluid power means resistant to normal hydraulic pressures in the well tubing, but movable when extra high pressure is applied thereto, and means to hold the valve in the moved position.

4. The combination of claim 2, wherein the valve moving means comprises a hydraulic pressure chamber and a piston therein subjected to pressure in the well tubing above the assembly, yieldable means urging the piston against such pressure and having strength to hold it against normal hydraulic pressure therein, and means to hold the valve in its moved position.

5. The combination of claim 4, wherein the means to hold the valve includes a hydraulically operated lock having a hydraulic plunger driven to valve-holding position by predetermined hydraulic pressures in the power fluid tube.

6. The combination of claim 4, wherein the means to hold the valve includes a check valve permitting inflow of fluid into the pressure chamber and throttling means to permit outflow of fluid therefrom only at a slow rate. I

7. A free pump apparatus for use in production fluid tubing, comprising: a pumping production unit having a barrel slidable in the production fluid tubing, the barrel having a through passage for transmitting production fluid from below the production unit to above it, and having a power oil passage extending laterally and opening through the side of the barrel for connection with a power oil supply, and extending downwardly for connection into the production unit, the barrel having sealing portions above and below the power oil passage that sealingly and slidably engage the walls of the tubing; control valve means in the barrel movable to first position to connect the upper and lower parts of the through passage, and also for connecting the lateral and downward parts of the power fluid passage, the valve means being movable to a second position to connect the lateral power fluid passage to the lower part of the through passage, to transmit power fluid to below the production unit and drive it to the surface; and means operable from the surface to shift the valve means from first to second positions, comprising a four-way valve connected into the power fluid and production fluid tubings, so as to be operable to apply power fluid pressure to either tubing, and means responsive to application of power fluid pressures above normal production fluid pressures to cause the control valve means to shift.

8. A free pump apparatus for use in production fluid tubing, comprising: a pumping production unit having a barrel slidable in the production fluid tubing, the barrel having a through passage for transmitting production fluid from below the production unit to above it, and having a power oil passage extending laterally and opening through the side of the barrel for connection with a power oil supply, and extending downwardly for connection into the production unit, the barrel having sealing portions above and below the power oil passage that sealingly and slidably engage the walls of the tubing; control valve means in the barrel movable to first position to connect the upper andlower parts of the through passage, and also for connecting the lateral and downward parts of the power fluid passage, the valve means being movable to a second position to connect the lateral power fluid passage to the lower part of the through passage, to transmit power fluid to below the production unit and drive it to the surface; and means operable from the surface to shift the valve means from first to second positions, said means including a pressure chamber, a check valve controlled passage admitting inflow of fluid from the tubing above the barrel into the pressure chamber but checking outflow, a piston-like member in said chamber and connected to the control valve means, yieldable resilient means urging the piston-like member to a first position, in which it positions the valve means in its first position, but yieldable to permit the piston-like member and the valve means to move to their second positions when the fluid pressure force produced in the chamber exceeds the force of the yieldable means, and a bleeder passage to provide restricted outflow of fluid from the chamber so that the piston-like member may return to its first position under action of the yieldable means when fluid pressure in the chamber is relieved.

9. The combination of claim 8 wherein the valve means has a latch surface, and the barrel has a plug slidably mounted through a wall to move into and out of latching engagement with the latching surface aforesaid, yieldable means urging the plug out of such engagement, a piston-like head on the plug subjected to pressure of the power fluid to be forced into such engagement, the inner end of the plug opening into the downwardly extending part of the power fluid passage so as to be subject to power fluid pressure on both ends except when the valve means is in its second position.

10. The combination of claim 9 wherein the plug has a bleeder passage through it.

References Cited in the file of this patent UNITED STATES PATENTS 2,653,545 Dempsey et a1 Sept. 29, 1953 

